Otto Salzer was the foreman of the mechanics at the Daimler Motoren Gesellschaft factory and a test driver. He became a works driver in 1903 and contested and won several races for Mercedes before and after the First World War.
In 1906 he was joined by Christian Lautenschlager, competing in his first race as a mechanic at the Ardennes circuit. They finished ninth after tire trouble.
He raced in the first Kaiser Preis in 1907 finishing 6th in his heat and 9th in the final. Then at the Grand Prix de l'ACF held in Dieppe, Mercedes entered three cars for Jenatzy, Salzer and Victor Hemery. Jenatzy retired on lap 7 and Salzer on lap 9. Victor Hemery came home 10th.
The event was repeated at Dieppe in 1908 where Mercedes had their new 12.8 litre cars with Salzer being joined by Willy Poge and Christian Lautenschlager. Lautenschlager won the race. Salzer set the fastest time of the race on his first lap but then retired on lap 2.
In 1913 he finished 4th in the III Grand Prix de France at Le Mans still driving for Mercedes.
In 1914 Daimler produced a new 4.5-liter car and Lautenschlager, Louis Wagner and Salzer finished a dominant 1-2-3 in the XIV Grand Prix de l'Automobile Club de France at Lyon. It is often said that the 1914 Mercedes Grand Prix team was the first occasion on which a racing team approached the sport as a technical exercise.
After 7h08m18s, Lautenschlager's white Mercedes was first to reach the Finnish. There was scattered applause only from the Germans but the crowd remained silent in shock and dismay. Wagner followed one minute and 36 seconds behind and Salzer arrived almost five minutes later. From 37 drivers at the start only eleven reached the finish. The German anthem in honor of the victors was not played.
Germany's defeat in WWI resulted in an absence form racing until 1922 when three of the old 1914 cars (4.5 litre 18/100) were entered on the Targa Florio for Lautenschlager, Salzer and Count Giulio Masetti, who was driving the ex-Salzer 1914 GP car, now in red livery. Lautenschlager finished tenth and Salzer 13th.
The cars were updated as much as was possible and did well on hillclimbs until 1927, with Salzer winning the first Solitude Hill Climb driving a 4 Cylinder Kompressor Mercedes in front of 100,000 spectators.